Clive Sinclair And The Small Home Computer Revolution
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Clive Sinclair And The Small Home Computer Revolution

The next step was to produce a kit. This turned out to be a tiny amplifier packaged into less than a 1 inch cube. At the time it was amazing and it packed components in vertically so tight that there wasn't a space to be seen. 

It was a success and more followed. Nearly all made a virtue of miniaturisation. At the time, although transistors had reduced the size of electronics and made it portable, most companies were not trying to make miniature products. Just building a circuit using transistors gave a sufficient size reduction to be impressive so why try any harder.




Sinclair on the other hand seemed to have a vision of what electronics would be like in the future and he wanted to make it happen instantly. To achieve this he had to design exceedingly clever circuits and find novel ways of mounting them on printed circuit boards to make the best use of space.

This sort of design does produce the smallest possible products but it can also make them difficult to actually produce and very difficult to fix. At first this didn't matter so much because they were being sold in kit form. An experienced constructor can cope with, and even enjoy, the challenge of getting a kit to work!

The kits continued to be produced. The Micro-6 radio smaller than a match box, the TR750 power amplifier and a range of pulse width modulated PWM amplifiers. Apart from being impossible to make work, the PWM amplifiers were the first excursion Sinclair Radionics took into digital electronics.




All of the kits were advertised in Sinclair's own instantly recognisable style. They made people want to own the product - they were exciting and all part of achieving the right image. This image extended to the first range of non-kit completely finished products, a range of Hi-Fi products impressed the enthusiasts with their modern looks.

In 1970 Sinclair Radionics moved in to a huge building, The Mill, on the banks of the Great Ouse. The company had grown from a seller of kits to a manufacturing company. It was also large enough to allow Sinclair to start to indulge his interests - or should that be obsessions. He wanted to build a tiny TV, and research on suitable tubes was started.

But what has all this got to do with computers? It should be said at this early stage in the story that Sinclair is not first and foremost a computer man. To him electronics was analog first and digital only much later.


At first his impact on the world of computing was almost incidental.

The first Sinclair product that we can classify as to do with computing was a calculator.

But what a calculator!

At a time (1972) when electronic calculators were desk bound the Sinclair Executive was a marvel of miniaturisation. It was the first pocket calculator and it wasn't very expensive. It won design council awards and was put on show at the Museum of Modern Art in New York. But it wasn't much of an innovation electronically. It used a standard chip with a, typical Sinclair, power saving trick of pulsing the power supply.




After the Executive came a range of lower priced pocket calculators.

These had a reputation for not being very reliable - although much of the trouble was due to a poor design for the on/off switch which was basically a spring contact on the printed circuit board. Then a scientific calculator was produced by reprogramming a standard off the shelf chip again another typically Sinclair trick.

Finally work did begin on a personal computer design - but the bottom fell out of the calculator market and the National Enterprise Board (NEB) took over Sinclair Radionics. The design was sold to Newbury - a maker of VDUs - and it turned up some time later as the NewBrain. A good and reliable machine but it lacked the flair of a true Sinclair product and used lots of discrete chips..

Financially things got worse at Sinclair Radionics. None of the products that had been launched to replace the lost calculator market were proving a success.


The incredibly innovative Black Watch - the first Quartz watch - was having so many reliability problems that most were returned for repair as soon as they were shipped. The miniature TV wasn't selling well and also had reliability problems. In the end, enough was enough and the NEB split Sinclair Radionics up.



While all this was going on Chris Curry had been looking after a small venture called Science of Cambridge. This company was to be Sinclair's lifeboat and indeed it turned into Sinclair Research soon after the loss of Sinclair Radionics.

Science of Cambridge operated in much the same way as the early Sinclair company. They produced kits and the advertising that they took was unmistakably "Sinclair" even though the magic name appeared nowhere. After a wrist calculator and a few other things the real breakthrough was the MK14.



The MK14


This was a microprocessor trainer - a membrane keyboard, LED display and that's about all. The MK14 was designed by Ian Williamson but it sort of counts as Sinclair's first computer. It certainly made him think hard about producing something a little better. It also inspired Chris Curry who, fired by a vision of better machines, set up Acorn with Herman Hauser. Their first product was the Acorn System 75 - a direct competitor to the MK14.

These computer trainers were very primitive. All you could do was to enter some machine code in hex - if you look at the keyboard you will see the abcde keys on the right. When you ran the program the result was shown in hex on the small display. It might not seem much by today's standards but at the time - it was a computer and one you could own. The possibilities were limitless - as long as the output was in hex. 



Last Updated ( Saturday, 13 August 2022 )